Making ready cylindrical plates



Oct. 27, 1953 F F. E. REILLY 2,656,790

I MAKING READY CYLINDRIC'AL PLATE Filed May 13, 1950 2 Sheets-Sheet 1 I.I Q uvwzmozc 1.2%: 7 .FRANK E. REILLY nrromvzrs,

Oct. 27, 1953 F. E. REILLY 2,656,790

MAKING READY CYLINDRICAL PLATE Filed ma 13, 1950 2 Sheets-Sheet 2.INVENTOR. FRANK E. REILLY Patented Oct. 27, 1953 MAKING READYCYLINDRICAL PLATES Frank E. Reilly, Winnetka, Ill., assignor toElectrographic Corporation, New York, N. Y., a corporation of DelawareApplication May 13, 1950, Serial No. 161,848

11 Claims.

esses, instrumentalities and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a parthereof, schematically L illustrate two modes of carrying out the processof the invention, and together with the description, serve to explainthe principles of the invention.

Of the drawings? Figure l is a fragmentary, exaggerated, sectional viewshowing an original letterpress or relief printing plate which is to beduplicated as a cylindrically curved printing plate for rotaryletterpress printing; t

Figure 2 is a similarview of a mat produced from the plate of Figure 1;

Figure 3 is a sectional view showing the operation of drying, scorchingand shrinking the mat of Figure 2;

Figure 4 is a view showing the casting of a stereotype from the shrunkmat;

Figure 5 is an exaggerated fragmentary sectional view of an underlayprepared from the plate shown in Figure 4;

Figure 6 is a fragmentary sectional View showing the bumping ormaking-ready of a cylindrically curved duplicateplate using the underlayof Figure 5;

Figure 7 is an exaggerated fragmentary sec tional view of the madereadyplate produced by the process of the present invention;

Figure 8 is an exaggerated sectional view showing the mat of Figure 2after it has been'treated so as to be used as an underlay in accordancewith the modification of the present invention; and

Figure 9 is a sectional View showing the bumping of the plate using thetreated matrix of Figure 8 as the underlay,

The present invention has for its object the provision of a novel andimproved method of making-ready cylindrically curved letterpressprinting plates so as to prepare them for use on the plate cylinder of arotary printing press. A further object of the invention is theprovision of a process by which the preparation of an underlay for usein the bumping of cylindrically curved plates is facilitated andexpedited, resulting in more economical made-ready and more accuratetreatment of the cylindrically curved plates. Still another object ofthe invention is the provision of a process of preparing an underlay fora curved printing plate from the original of the plate which underlaywill accurately re ister with the plate when it is positioned againstthe underside thereof.

The preparation of underlays for use in making-ready cylindricallycurved relief printing plates heretofore has involved laborious, carefuland expert preparation of an underlay from a proof of the original orduplicate plate, the size and position of the different areas of theunderlay being changed from those of the original proof so that theunderlay will be in correct radial register with the plate when theunderlay is applied to the concave or underside of the plate. It hasalso been possible to prepare such under lays with mechanical aids, butthis method requires the provision of special equipment not ordinarily.found in the plate-making or printing establishment, and consequentlysuch a process is not one of general application.

In the preparation of an underlay for a cylindrically curved plate ofthe size conventionally used for printing a magazine page, the underlaywill be oftentimes as much as one-half inch shorter than the overlay orproof of the original, the difference in length between the originalproof and the underlay being determined by the diameter of the cylinder,the length of the plate and the thickness of the plate. The differencein length must be distributed uniformly along the length of the underlayin order to secure the desired, correct radial register of the underlaywith the plate. 7

In accordance with the present invention, the underlay is prepared froma stereotype mat of the kind which exhibits substantial and controllableshrinking in one direction only as the mat is dried and scorched. Forthis purpose the con ventional dry fiong is used, and is positioned onthe original plate during the molding operation so that its shrinkagewill be in a direction corresponding to the circumferential extent ofthe plate to be made-ready. Thus in the mak ing-ready of an electrotypewhere the cylindrically curved plate is an accurate duplicate of theoriginal plate, the mat would be molded from the original plate, andafter shrinkage would be used to form the underlay, by removal of theface of the mat so as to provide a smooth surface. Alternatively, astereotype plate may be cast from the mat, and the stereotype plateproved on underlay stock, so that the proof impression forms an accurateguide in the cutting of the underlay. If the original plate is notavailable, or if the curved plate is to be formed by stereoty thestereotype mat to be used in forming the underlay would be molded fromthe duplicate cylindrically curved plate.

Referring now in detail to the accompanying drawings in which Figures 1to 7 illustrate the present preferred and typical manner of carrying outthe process of the present invention, Figure 1 shows a relief orletterpress printing form H) which may be a type form. oraphotoengraving, having solid printing areas l2, areas of intermediatetone I4, and nonprinting areas Hi. In a photoengraving the areas l2, l4and It might correspond to the blacks, halftones and whites,respectively, while in a type form the areas l2, l4 and [B would be theheavy bold letters, the fine light letters, and the non-printing areas,respectively.

A stereotype mat is prepared from the original form H) in accordancewith conventional stereotype practice, care being taken that thedirection of shrinkage of the mat is known, and that the fiong is sopositioned on the form it that the shrinkage will be in a directioncorresponding to the circumference of the printing cylinder on which theduplicate plate is to be mounted for printing. Such a-stereotype flongusually -comand about 0.050 to 0.100" in thickness, the sheet beingcomposed of a mixture of fibrous material and cla and being quite moistso that it is moldable under relatively heavy pressure. Such flongs aregenerally called dry mats and on drying exhibit almost no shrinkage inone direc tion but exhibit a controlled amount of shrink: age at rightangles to the first 'direction, the amount of the controlled shrinkagedepending upon the conditions of drying, particularly the time andtemperature-of'drying so that :a' shrinkage of 3% to 6% pr 7% in thelength of thermal: is easily obtained, while a shrinkage of less than 1%in the width of the mat occurs.

Figure 2 schematically illustrates a fragmem tary section of the mat 20as molded from the original form In, and. as will ,be-seen the back ofthe mat is at several different elevations corre sponding .to thevarious portions of the original form I0. the solid portions l2 are thehighest, the portions '24 overlying the intermediate tones M are ofintermediate elevation while the areas '26 overlying the white ornonprinting areas are the lowest. The difference in'elevationbetweentheportions 22 and 26 are produced by resiliency of the paddingused in molding the mat 20, this padding usually being in the form of ablanket or a thick layer of newsprint positioned between the flong andthe upper platen of the molding press.

Thus, as shown, the areas 22 overlying I I 4 This operation is shownschematically in Figure 3 where the mat 2D is positioned face down upona cylindrically curved metal shell 28 which is heated by a suitableheater 30, the mat being held to conform to the shell 28 by means of acover mem ber 32. When the drying and scorching operation has beencompleted, the mat has shrunk along its circumferential direction and isthen used for the casting of a conventional stereotype plate 34 whichmay be either a fiat plate or a cylindrically curved plate. In casting aflat plate .from 'a matwhich has been scorched in a cylindri' cal shape,the mat may be flattened out and then used in a conventional flatcasting box, or alternatively the mat may be flattened and scorched in aflattened condition. The stereo-type plate 34 is an accuratereproduotionof the original form It] except that the plate 34 is shouter along thedirection of the circumference of the eventual printing cylinder. 1

The stereotype plate 34 is then proved on a sheet of underlay stock 36,which underlay stock usually comprises a relatively heavy sheet of hardpaper 38, such as manila. tag, on which are provided one or more layersof thin paper 40, the thin layers usually being about .002 or .003 of aninch thickness. Preferably the underlay stock is of the kind disclosedin the prior patent to Bishop No. 2,088,398, although any conventionalunderlay stock may be used. The proof of the stereotype plate 34 on:theunderlay stock '36 forms an accurate guide which may be rigorouslyfollowed by the operator in cutting through the thin layers 40 for theirremoval. When completed, the underlay comprises the heavy sheet 38, andthe overlying adherent layers 40 which have been removed in portions toprovide relatively thick areas =42 corresponding to the solids !2, areas"of intermediate thickness 44 corresponding to the intermediate tones,and areas of minimum thickness 46 corresponding to the whites ornonprinting areas I6. 7

The underlay which is'shown schematically and in exaggerated form inFigure 5 may be used in that condition as a press underlay, in case theplate is not to be bumped, and in that case the underlayis positioned onthe concave back of the finished cylindrically curved printing plate inregister with the various areas of theplate, and remains with the plate.as it. is clamped to the printing cylinder and thereafter printed.

However, the underlay is preferably used for the bumping of thecylindrically curved press plate, and'for this purpose is similarlymounted on the concave or backside of the cylindrically curved.electrotype or other duplicate plate in radial-register with the designon the face of the plate. In case the plate is to be bumped,aconventional overlay is prepared, andcomprises a sheet of'uneven'thickness which, except for its circumferential length, is thecomplement of the underlay. Such an overlay 50 is shown in Figure 6 andincludes a heavy base sheet 5| on which the areas of thin paper form thethick areas 52. the areas of intermediate thickness 54, and the areas ofminimum thickness 56 corresponding to the areas i6, 14, and l2,respectively of the original form [0, and likewise corresponding to theareas 42, 44 and '46, respectively, of the underlay .36. The overlay ispositioned on the face of the electrotype or other cylindrically curvedplate .60, and the assembly comprising the underlay .36, the overlay 50and the plate 60 arepassed through a pair of powerful pressure rollers62which are adjusted to exert high pressure on the assembly so as todeform the plate 60 in accordance with the thickness of the variousportions of the underlay 36 and the complementary overlay 50. theoverlay 50 act as male and female dies and after the bumping operationhas been completed, a plate is produced which is schematically shown inFigure 7. As there shown, the solid areas 62 have been raised above theintermediate printing areas 64, and the areas 62 and 64 are both raisedwith respect to the whites or nonprinting areas 66. The bumped plate 60is then finished by shaving or boring its concave or rear face so as toprovide a truly cylindrical concave face 68 which corresponds accuratelyin curvature to the surface of the printing cylinder on which the plateis to be mounted and printed. As shown by the dot-dash line in Figure'7, the portion of the plate indented by the underlay 36 during thebumping operation is completely removed during the boring or shavingoperation which reduces the plate to the desired final thickness.

In accordance with the modified form of the process of the presentinvention, the underlay is prepared directly from the dried and scorchedmat upon completion of the operation shown in Figure 3. In accordancewith this modification of the invention, the mat 20 with its back havingthe areas 22, 24 and 26 corresponding to the solids, intermediate tonesand highlights or nonprinting areas of the original form, is treated toremove its face and to provide a smooth, flat or cylindrically curvedsurface 10. This operation of removing the molding face of the mat maybe performed in any desired manner, as by milling or grinding, andFigure 8 of the drawing shows the dot-dash lines the portion of themolding face of the mat which is thus removed. The dried, scorched andshrunken mat 20, the molding face of which has been removed to provide asmooth surface, now forms an underlay I2 and is positioned against theback or concave face of the cylindrically curved plate 60 in radialregister with the plate and with the overlay 50. With the parts in thisposition, the plate underlay and overlay are passed between the powerfulpressure rollers 62 so as to deform the plate 60 after which theirregularities in the concave back of the plate 60 are removed by boringor shaving to produce a plate similar to that shown in Figure '7.

The invention in its broader aspects is not limited to the specificprocess and steps shown and described but departures may be madetherefrom within the scope of the accompanying claims without departingfrom the principles of the invention and without sacrificing its chiefadvantages.

What is claimed is:

1. The process of preparing an underlay for making ready a cylindricallycurved relief printing plate which comprises forming a stereotype matfrom a printing plate or form of the same size and design as the plateto be made ready and a flong which shrinks on drying principally in adirection circumferentially of the cylindrical plate to be underlaid.drying the mat until the mat is in substantial radial register with theconcave face of the curved plate with which it is to be used and formingfrom the mat an underlay having thicker portions corresponding to thesolid printing areas of the curved plate and in radial registertherewith.

2. The process claimed in claim 1 in which the In this operation theunderlay 36 and back of the mat is raised and the face of the mat isremoved to provide a smooth surface.

3. The process of making ready a curved plate which comprises producingan underlay in accordance with claim 2 and using it with a complementaloverlay to bump the curved plate.

4. The process claimed in claim 1 in which a stereotype is cast from theshrunk mat, the stereotype is printed on a sheet of underlay stock whichis then out to form an underlay in accordance with the printedimpression thereon.

5. The process of preparing an underlay for making ready a cylindricallycurved relief printing plate which comprises forming a stereotype matfrom a flat printing plate or form of the same size and design as theplate to be made ready and a fibrous and slightly moist fiong whichshrinks on drying principally in a direction circumferentially of thecylindrical plate to be underlaid, drying and scorching the mat untilthe mat is in substantial radial register with the concave face of thecurved plate with which it is to be used and forming from the mat anunderlay having thicker portions corresponding to the solid printingareas of the curved plate which will radially register with the curvedplate to be underlaid.

6. The process claimed in claim 5 in which the back of the mat is raisedand the face of the mat is removed to provide a smooth surface.

'7. The process claimed in claim 5 in which a stereotype is cast fromthe shrunk mat, the stereotype is printed on a sheet of underlay stockwhich is then cut to form an underlay in accordance with the printedimpression thereon.

8. l'he process of making ready cylindrically curved relief printingplates which comprises forming a stereotype mat from a printing plate orform of the same size and design as the plate to be made ready and afiong which shrinks on drying principally in a directioncircumferentially of the cylindrical plate to be underlaid, drying themat until the mat is in substantial radial register with the concaveface of the curved plate with which it is to be used and forming fromthe mat an underlay having thicker portions corresponding to the solidprinting areas of the plate which will radially register with the curvedplate when used as an underlay, forming an overlay for the curved platehaving thicker portions corresponding to the nonprinting areas of thecurved plate, positioning the overlay over the face of the cylindricallycurved plate and the underlay on the back of the cylindrically curvedplate and deforming the plate by pressure applied radially of the plateto be made ready to raise the solid areas of the printing face of thecurved plate.

9. The process claimed in claim 8 in which the back of the mat is raisedand the face of the mat is removed to provide a smooth surface.

10. The process claimed in claim 8 in which a stereotype is cast fromthe shrunk mat, the stereotype is printed on a sheet of underlay stockwhich is then out to form an underlay in accordance with the printedimpression thereon.

11. The process of making ready cylindrically curved relief printingplates which comprises forming a stereotype mat from a flat printingplate or form of the same size and design as the plate to be made readyand a fibrous and slightly moist flong which shrinks on dryingprincipally in a direction circumferentially of the cylindrical plate tobe underlaid, drying the mat until the mat is in substantial radialregister with the concave face of the curved plate with which it is asan underlay, forming an overlay for the curved plate having thickerportions corresponding 'to the non-printing areas of the plate,positioning the overlay over the face of the cylindrically curved plateand the underlay on the back of the cylindrically curved plate anddeforming the plate by pressure applied radially of the plate to raisethe solid areas of the printing face of the curved plate.

FRANK E. REILLY.

References Cited in the file of this patent Number UNITED STATIESPATENTS Name Date Droitcour Oct. 10, I911 Dittman May 6, 1913 BungayFeb. 26, 1952

